1. Field of the Invention
The present invention relates to damping mechanisms, and more particularly to a piston damping mechanism providing damping effects at the end of compression and extension strokes of a piston, using one unidirectional damper unit.
2. Description of the Related Art
Among the many devices that find use in the aircraft industry are spring mechanisms facilitating the closing of doors and other such closures. Typically, the spring mechanisms comprise a highly loaded spring assembly. A closure using this type of spring mechanism generally will swing at high speed in an xe2x80x9copeningxe2x80x9d direction as well as a xe2x80x9cclosingxe2x80x9d direction, and as a result high impact loads are incurred, which typically lead to early failure.
In order to diminish any possibility of damage, either to property or persons, spring mechanisms used as xe2x80x9cdoor closersxe2x80x9d, to which such mechanisms are often referred and to which this invention relates, incorporate some form of damping mechanism, such as hydraulic dampers. Until recently, such xe2x80x9cdoor closersxe2x80x9d typically featured unidirectional damping capabilities, most with valve mechanisms to allow easy opening by overriding the damping when the door is opened, and by restorimg damping whenever the door is released for closing.
However, it has been found that such valve mechanisms can be eliminated without making the opening of a door unduly burdensome, by incorporating a two-way damping apparatus.
The prior art is replete with examples of two-way damping devices for use in the opening and closing of doors. For example, U.S. Pat. No. 4,917,222 to Bacardit and U.S. Pat. No. 5,170,530 to Kopec et al teach two types of two-way damping devices. The former (Bacardit) teaches a shock absorber in which two-way motion of the piston is slowed by an inertial valve which comes into play when the piston moves at a rate of acceleration that exceeds a certain predetermined value. The latter (Kopec et al.) teaches the use of a damper disposed in a cylinder located within the housing of a shock absorbing door closer apparatus, wherein the damper cooperates with incompressible hydraulic fluid contained in the cylinder to slow the motion of the piston in either of two oppositely directed motions.
Against this background of known technology, the applicant has developed a novel damping mechanism for slowing movement of a piston within a cylinder in either of an extension stroke or a compression stroke. The damping mechanism of the present invention is an improvement over existing off-the-shelf designs.
It is therefore an object of the present invention to provide a novel damping mechanism for slowing motion of a piston in a cylinder in either of the compression stroke or the extension stroke, while overcoming all the drawbacks and disadvantages of similar damping systems known in the art.
Another object of the present invention is to provide a piston and cylinder incorporating a damping apparatus that is constrained for reversible linear movement within the cylinder during extension and compression strokes of the piston, and which enables damping of the motion of the piston when the piston reaches a predetermined end region of the extension stroke or the compression stroke.
Other objects, advantages and features of the invention will become more apparent, as will equivalent structures which are intended to be covered herein, with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings in which: